Glossary
Inscriptions
Arbitrary data — images, text, JSON, code — embedded into a Bitcoin transaction's witness via the Ordinals protocol, creating Bitcoin-native artifacts.
An inscription is the payload attached to a satoshi via the Ordinals protocol. The data — up to roughly 4 MB after Taproot's witness discount — is encoded in a transaction's witness and permanently stored in Bitcoin's blockchain.
Inscriptions are how Bitcoin NFTs work in practice, and how BRC-20 fungible tokens are encoded (as JSON inscriptions interpreted off-chain). The model has been controversial: some operators see it as a creative new use case for Bitcoin block space, others as spam crowding out monetary transactions.